English
Related papers

Related papers: On the Maximal Value of the Turbulent alpha-Parame…

200 papers

Building upon our first paper [Hu, K.X, & Hu, Y. J. (2025). Hydroacoustic Absorption and Amplification by Turbulence, arXiv:2512.07920], the present work conducts a more in-depth investigation into the impact of turbulence on hydroacoustic…

Fluid Dynamics · Physics 2026-03-04 Kai-Xin Hu , Yue-Jin Hu

When wind blows over the surface of a viscous liquid, a clear transition from irregular small-amplitude streamwise-oriented wrinkles to well-defined nearly two-dimensional regular waves is observed at a critical wind velocity. We examine…

A new mechanism for the enhanced generation of compressible fluctuations by Alfven waves is presented. A strongly nonlinear regime of Alfven wave phase-mixing is numerically simulated in a one-dimensionally inhomogeneous plasma of finite…

Astrophysics · Physics 2007-05-23 V. M. Nakariakov , D. Tsiklauri , T. D. Arber

Thin viscous Keplerian accretion disks are considered asymptotically stable, even though they can show significant dynamic activity on short timescales. In this paper the dynamics of non-axisymmetric hydrodynamical disturbances of disks are…

High Energy Astrophysical Phenomena · Physics 2015-05-13 Paola Rebusco , Orkan M. Umurhan , Wlodek Kluzniak , Oded Regev

The ability of streamwise-travelling waves of spanwise velocity to reduce the turbulent skin friction drag is assessed in the compressible regime. Direct numerical simulations are carried out to compare drag reduction in subsonic, transonic…

Dynamo action owing to helically forced turbulence and large-scale shear is studied using direct numerical simulations. The resulting magnetic field displays propagating wave-like behavior. This behavior can be modelled in terms of an…

Astrophysics · Physics 2011-02-11 P. J. Käpylä , A. Brandenburg

We study the effect of an imposed vertical magnetic field on the turbulent mass diffusion properties of magnetorotational turbulence in protoplanetary discs. It is well-known that the effective viscosity generated by the turbulence depends…

Astrophysics · Physics 2009-11-11 Anders Johansen , Hubert Klahr , Antony J. Mee

We performed high resolution numerical simulations of homogenous and isotropic compressible turbulence, with an average 3D Mach number close to 0.3. We study the statistical properties of intermittency for velocity, density and entropy. For…

Chaotic Dynamics · Physics 2009-11-13 Roberto Benzi , Luca Biferale , Robert Fisher , Leo Kadanoff , Donald Lamb , Federico Toschi

We report an experimental and numerical study of turbulent fluid motion in a free surface. The flow is realized experimentally on the surface of a tank filled with water stirred by a vertically oscillating grid positioned well below the…

Chaotic Dynamics · Physics 2009-10-31 W. I. Goldburg , J. R. Cressman , Z. Voros , B. Eckhardt , J. Schumacher

We examine the effects of the different viscosity prescriptions and the magnitude of the viscosity parameter, $\alpha$, on the structure of the slim disk, and discuss the observational implications on accretion-flow into a stellar-mass…

Astrophysics · Physics 2015-06-24 Ken-ya Watarai , Shin Mineshige

Turbulence is a fundamental parameter in models of grain growth during the early stages of planet formation. As such, observational constraints on its magnitude are crucial. Here we self-consistently analyze ALMA CO(2-1), SMA CO(3-2), and…

Earth and Planetary Astrophysics · Physics 2018-04-11 Kevin M. Flaherty , A. Meredith Hughes , Richard Teague , Jacob B. Simon , Sean M. Andrews , David J. Wilner

We obtain high spatial and spectral resolution images of the CO J=2-1, CN N=2-1 and CS J=5-4 emission with ALMA in Cycle~2. The radial distribution of the turbulent broadening is derived with three approaches: two `direct' and one…

In this letter, we present numerical calculations made to investigate the possible resolution dependence of the Shakura & Sunyaev (1973) viscosity parameter alpha from local magnetohydrodynamic simulations of the magnetorotational…

Astrophysics · Physics 2007-05-23 P. J. Kapyla , M. J. Korpi

We present a systematic investigation of the effects of roughness geometry on turbulent Rayleigh-B\'enard convection (RBC) over rough plates with pyramid-shaped and periodically distributed roughness elements. Using a parameter $\lambda$…

Fluid Dynamics · Physics 2017-07-26 Yi-Chao Xie , Ke-Qing Xia

(abridged) Context: Turbulent diffusion of large-scale flows and magnetic fields play major roles in many astrophysical systems. Aims: Our goal is to compute turbulent viscosity and magnetic diffusivity, relevant for diffusing large-scale…

Solar and Stellar Astrophysics · Physics 2020-04-29 Petri J. Käpylä , Matthias Rheinhardt , Axel Brandenburg , Maarit J. Käpylä

We study linear transient dynamics in a thin Keplerian disc employing a method based on variational formulation of optimisation problem. It is shown that in a shearing sheet approximation due to a prominent excitation of density waves by…

High Energy Astrophysical Phenomena · Physics 2015-06-19 V. V. Zhuravlev , D. N. Razdoburdin

We present full 2 Pi global 3-D stratified MHD simulations of accretion disks. We interpret our results in the context of proto-planetary disks. We investigate the turbulence driven by the magneto-rotational instability (MRI) using the…

Earth and Planetary Astrophysics · Physics 2015-05-27 M. Flock , N. Dzyurkevich , H. Klahr , N. J. Turner , Th. Henning

Turbulent viscosity is frequently used in accretion disk theory to replace the microphysical viscosity in order to accomodate the observational need for in- stabilities in disks that lead to enhanced transport. However, simply replacing the…

Astrophysics · Physics 2015-05-13 Alexander Hubbard , Eric G. Blackman

The effect of random surface roughness on hydrodynamics of viscous incompressible liquid is discussed. Roughness-driven contributions to hydrodynamic flows, energy dissipation, and friction force are calculated in a wide range of…

Soft Condensed Matter · Physics 2009-11-07 I. V. Ponomarev , A. E. Meyerovich

The possible transition to the so-called ultimate regime, wherein both the bulk and the boundary layers are turbulent, has been an outstanding issue in thermal convection, since the seminal work by Kraichnan [Phys. Fluids 5, 1374 (1962)].…